A new 4×14 evaporator, six branch circuits, and one head-tank float that nearly drained itself.

The customer and the system

An East Craftsbury sugarbush, currently 1,800 taps growing to 3,500 over two seasons. Old rig was a 2×6 wood-fired arch dating to the 1990s; new rig is a 4×14 oil-fired with a steam-away hood and an automated draw-off. The customer had pre-bought the evaporator from CDL and the RO from Lapierre; our scope was the building electrical and the bonding to all stainless equipment. The existing service was 200A residential single-phase from a 2014 J-01 of ours, headroom for 3,500 taps was tight; we noted it and the customer accepted the risk to defer a service upgrade.

The motor and load list

Equipment	HP	V/Phase	FLA	Inrush (typical)	Soft-start?
Tubing-vacuum pump (Lapierre)	7.5	240/1	32 A	192 A	Yes (8s ramp)
RO high-pressure feed (Lapierre)	5.0	240/1	22 A	132 A	Yes (8s ramp)
RO booster	1.5	120/1	14 A	52 A	No
Concentrate transfer	1.0	120/1	9 A	34 A	No
Hood fans (×2)	0.75 ea	120/1	7 A ea	21 A ea	No
Heat trace (perimeter sap line)	—	240/1	14 A	—	—
Lighting (LED high-bay × 6)	—	120/1	3 A	—	—

The continuous load running everything together comes out at ~74 A on the 240V side. Inrush from a cold start of the vacuum pump (the largest motor) is the controlling factor: 192 A inrush against a 200A service is uncomfortable. Soft-starting the vacuum cuts the inrush to 70 A, which the existing service handles cleanly.

The float problem

Day 4, we had the head-tank float wired and tested. Day 5, with the system pressure-tested but not running production, the customer ran a wash cycle through the RO and let it idle. The float closed; the upstream concentrate-transfer pump shut off correctly. Forty minutes later, the head tank had drained itself: the evaporator was still pulling concentrate to a hot pan, and the float-down signal was not re-energizing the upstream pump.

What we found: the float switch was a normally-open mercury-tilt unit (CDL standard), and the manufacturer wiring diagram had two interpretations. The contractor we'd subcontracted the controls to had wired it as "fill until full" rather than "fill on demand"; the float closed at the high-water mark and shut off forever. The CDL panel's PLC did support the second interpretation, but only if the float was on a Class 2 input that we hadn't selected.

The fix took two hours: re-wired the float to the correct PLC input, set the bake-out trigger to also re-enable the upstream pump, and added a second float at the half-full mark as a redundant interlock. We added a permanent labeled diagram inside the panel for whoever services it next.

What we wired (final)

Vacuum pump branch

240V single-phase 50A breaker, #6 NM-B in EMT, soft-start (Eaton SVX) ahead of disconnect.

RO panel branch

240V single-phase 30A, dedicated, with Type-2 SPD on the breaker.

RO booster + transfer

120V each, 20A breakers, GFCI.

Hood fans

120V on a single 20A circuit with motor-rated switch.

Head tank float

Class 2 wiring back to CDL panel, redundant float at half-full.

Heat trace

240V 30A circuit with line-voltage thermostat; contactor drops out at 35°F per our standard practice.

Lighting

Two 120V circuits, dimmable over the boil, full bright over canning.

Bonding

#4 copper bus tied evaporator hood, RO chassis, head tank legs, vacuum pump frame to building grounding electrode system.

Final billing

Labor (journey + apprentice 3-yr, with a half-day master assist)

64 hrs · $5,696

Materials (EMT, NM-B, soft-start, SPD, two floats, contactor)

$2,180 + 12% = $2,442

Soft-start surcharge (sourcing fee)

4% of $920 = $37

VT DFS permit

$165

Working-farm discount (8% labor)

− $456

Total

$7,884

Customer paid net-15. The system ran clean through the 2026 sap run; the customer reports total fuel use down 18% vs. the old wood-fired rig at equivalent yield, mostly because the 4×14 + RO is just more efficient, but partly because the soft-started vacuum doesn't drop the boil temp on every cold start.

Why we like this job

The work was straightforward by sugarhouse standards. The float problem was a useful reminder that even on a manufacturer's stock panel, we will trace every input and output once before we sign off. The two hours we spent that day saved the customer either a flooded evaporator or a starved one in March, when neither outcome is fixable inside the run.

Related: J-03 Sugarhouse power and the almanac entry on power-quality dynamics on the rural feeder during the run.